International

In 2006, Navistar introduced the International ProStar long-haul tractor, replacing the 9400i, and began phasing out the "Thousand-Series" nomenclature. In 2008, the DuraStar replaced the 4000 series, and the WorkStar replaced the 7000 series, while the TranStar name was revived for regional-haul tractors. Sales of all three XT models ceased after 2008.

In 2005, Navistar purchased Workhorse Custom Chassis, LLC, a manufacturer of step-van and motor home chassis, to re-enter the delivery van market. Workhorse briefly offered the MetroStar chassis-body product. In 2012, Navistar shut down Workhorse to cut costs. AMP Electric Vehicles acquired Workhorse's assets in 2013, later rebranding as Workhorse Group Inc. in 2015.

2010s

In 2010, Navistar revived plans to move its headquarters from Warrenville, IL, to Lisle, Illinois, creating 3,000 permanent jobs and 400 construction jobs. The company invested $110 million in the new campus, with $65 million in state incentives. In 2011, Navistar phased out its Truck Development and Technology Center (TDTC) in Fort Wayne, Indiana, laying off 130 employees. By 2015, the TDTC was closed with 300 employees relocating to Illinois, while others retired or found new work.

In June 2012, hedge fund MHR Fund Management LLC took a 13.6% stake in Navistar, triggering a poison pill defense. In August 2012, Navistar adopted Cummins engines and Selective Catalytic Reduction (SCR) technology. President Dan Ustian retired, and in September 2012, activist investor Carl Icahn criticized the company for mismanagement. Several executives left the company between 2012 and 2013, including Ustian and other key leaders.

Navistar faced layoffs and plant closures, including 500 jobs in August 2012 and 200 more in September 2012. The Garland, Texas plant closed in 2013, costing 900 jobs. Additional job cuts occurred between 2013 and 2014 as part of a broader cost-cutting plan.

Navistar cut SG&A costs by 16% in 2013 and product development spending by 24%. The company sold off non-core businesses, including its RV and Workhorse Chassis units. In 2014, Navistar moved engine production from Huntsville, Alabama to Melrose Park, Illinois, eliminating 280 jobs.

In 2014, General Motors and Navistar announced a partnership to develop medium-duty trucks, leveraging both companies' expertise. Production began in 2018 at Navistar’s Springfield, Ohio facility.

In 2016, Navistar entered a strategic alliance with Volkswagen Group's truck division, Traton SE, which purchased a 16.6% stake in Navistar for $256 million. This partnership aimed at improving Navistar’s technology and procurement capabilities.

2020s

On January 30, 2020, Traton announced a proposal to acquire all outstanding shares of Navistar. In April 2021, the Brazilian competition regulator CADE initiated a review of the pending merger, distributing market surveys to 35 companies. The acquisition was completed on July 1, 2021, making Navistar a subsidiary of the Traton Group. As part of the merger, Navistar International Corporation was renamed Navistar, Inc.

On July 15, 2020, Navistar entered into a partnership with TuSimple, a company specializing in autonomous trucking technology, to develop Level-4 autonomous semi-trucks. Production was scheduled to begin in 2024. While the total investment remained undisclosed, Navistar acquired a minority stake in TuSimple as part of the agreement.

On September 25, 2024, Navistar announced its rebranding to International Motors, LLC, effective October 1, 2024. The company also introduced a new logo and corporate identity as part of the transition.

In April 2025, citing tariffs and a freight recession, International cut 900 jobs from its Escobedo plant. A further 300 corporate employees were laid off in February 2026. On March 30th, 2026, the company announced the sale of its Springfield, Ohio facilities to Roshel, a defense manufacturer based in Canada. After the expiration of International's production contract with General Motors on September 30th, 2026, Roshel will take over the facility. Approximately 1,341 employees will be terminated, and production of the CV model (and the related Chevy Silverado 4500-6500 models) will cease.

MWM International Motores (2005–2022)

In 2005, Navistar purchased MWM International Motores, a Brazilian engine manufacturer formerly associated with Deutz AG. MWM was sold to Tupy S.A. in 2022.

Engines (1986–present)

In 1986, Navistar was formed from the engine division of the former International Harvester (alongside the truck division). In a continuation from its predecessor, International produced both gasoline and diesel-fueled engines for its medium-duty trucks and some heavy-duty trucks, offering second-party engines as an option. Class 8 trucks offered second-party diesel engines (from Caterpillar, Cummins, and Detroit Diesel). From International Harvester, International inherited production of the SV-series gasoline V8, IDI diesel V8, DV-series diesel V8, and DT466 inline-6. After 1986, the production of gasoline engines ended, shifting to diesel-powered engines entirely. During the 1980s, Navistar began an expansion of its engine families. For 1986, a 7.3L version of the IDI was introduced; the engine supplanted the long-running DV-series V8 by the end of 1988; the same year, it became an option in Ford trucks. For 1987, the DT inline-6 engine family was expanded to a second engine, as the DT360 was introduced (competing directly against the Cummins 6BT).

During 1994 production, the IDI V8 was replaced by the direct-injection T444E V8, sharing little more than its displacement with its predecessor; the T444E became the first Ford PowerStroke engine. While the DT360 was withdrawn (largely replaced by the T444E), the DT466 (now the DT466E) was joined by the larger DT530E (competing primarily against the Cummins C8.3). For the 2000s, International began developing engines to comply with updated emissions standards for commercial vehicles. During 2003, the T444E was discontinued and replaced the VT engine family, introduced by the VT365 V8. For 2004, the DT engines received modernized fuel injection and a redesigned turbocharger; the DT530 was replaced by the DT570 (sized between the Caterpillar C9 and the Cummins ISL). In place of using Selective Catalytic Reduction (SCR) to treat engine emissions, International adopted Exhaust Gas Recirculation (EGR), a configuration used with success in automobiles with gasoline engines.

For 2007 emissions compliance, International launched the "MaxxForce" branding for its diesel engines. The VT engine family consisted of the 4.5-liter MaxxForce 5 V6 and the 6.4-liter MaxxForce 7 V8 (replacing the VT365). The DT466 became the MaxxForceDT, with the DT and HT570 becoming the MaxxForce 9 and 10, respectively. For its Class 8 trucks, the company introduced "large-bore" engines for the first time, introducing the 10.5L MaxxForce 11 and the 12.4L MaxxForce 13. After the 2010 model year, Ford ended its engine supply agreement with International, continuing the PowerStroke range under its own designs. The MaxxForce 7 and DT engines were updated with twin turbochargers to improve emissions compliance.

Following several years of difficulty reliably matching 2007 and 2010 emissions compliance, International chose to end diesel engine production of their medium duty and 15L engines following the 2014 model year, replacing the MaxxForce 7 and MaxxForceDT with the Cummins ISB6.7 and ISL9, and ISX15, respectively.

In 2015, International launched the N13 to replace the MaxxForce 13, bringing selective catalytic reduction (SCR) technology to replace the previous emission control strategies.

In 2017, International launched the A26 12.4L inline-6. This was the next iteration of Navistar's 13L going to a single variable geometry turbo in place of the previous dual turbo setup and a smaller exhaust gas recirculation system.

In 2022, Navistar introduced the International S13 engine. Unlike the A26, the S13 engine operates on low revolutions and higher torque equating to fewer fuel injections and less fuel consumption.

Plug-in hybrid electric bus

The U.S. Department of Energy announced in 2009 the selection of Navistar Corporation for a cost-shared award of up to US$10 million to develop, test, and deploy plug-in hybrid electric vehicle (PHEV) school buses. The project aims to deploy 60 vehicles for a three-year period in school bus fleets across the nation. The vehicles will be capable of running in either electric-only or hybrid modes that can be recharged from standard electrical outlets. Because electricity will be their primary fuel, they will consume less petroleum than standard vehicles. To develop the PHEV school bus, Navistar will examine a range of hybrid architectures and evaluate advanced energy storage devices, with the goal of developing a vehicle with a 40-mile (64 km) range. Travel beyond the range will be facilitated by a clean diesel engine capable of running on renewable fuels. The DOE funding will cover up to half of the project's cost and will be provided over three years, subject to annual appropriations.

eStar electric van

The eStar was an all-electric van. Production began in March 2010 and first deliveries began two months later via its Workhorse Group division. The technology used in eStar was licensed to Navistar in 2009 in a joint venture with Modec and Navistar bought the intellectual property rights from the Modec's bankruptcy administrators in 2011. The introduction of the eStar was supported by a US$39.2 million U.S. Department of Energy stimulus grant under the 2009 American Recovery and Reinvestment Act. The eStar had a 5,100 lb (2,300 kg) payload capacity available with a 14- or 16-foot cargo box. The vehicle was powered by a 70 kW 102 hp electric motor powered by an 80kWhr lithium-ion battery pack supplied by A123 Systems, and also used regenerative braking. The electric van had a range of 100 mi (160 km), and a full charge took between 6 and 8 hours. By May 2010 the eStar had received U.S. Environmental Protection Agency (EPA) and CARB certifications. The eStar also met all Federal Motor Vehicle Safety Standards (FMVSS). The first vans were delivered in May 2010 to FedEx Express for use in Los Angeles. Other customers included Pacific Gas and Electric Company (PG&E), The Coca-Cola Company, and Canada Post. The eStar had a price of US$150,000. Navistar discontinued the eStar van in March 2013, as part of a corporate restructuring plan to focus on current profitability.

Navistar Defense LLC (2003–present)

In 2003, Navistar created Navistar Defense. While Navistar had manufactured vehicles for the military long into its existence as International Harvester, Navistar Defense would operate as a freestanding division within the company. Alongside the MaxxPro MRAP and the MXT-MV, Navistar Defense has developed military variants of the 5000 and 7000 severe-service trucks (today, the HX and HV-Series on-road).

Failed engine strategy

In 2001, the company under then CEO Dan Ustian faced numerous United States Environmental Protection Agency (EPA) regulations to reduce the amount of nitrogen oxides and soot emanating from diesel engines. Despite the change in the compliance arena, the regulations would not begin to be phased in until 2007, with full implementation slated for 2010.

Ustian had multiple engineering paths available. Among them were Selective Catalytic Reduction (SCR), Exhaust Gas Recirculation (EGR), or the use of nitrogen oxide absorbers. All required more engineering and development to achieve compliance. Ustian believed truckers did not want to bother with an extra tank of fluid after treatment. As a result, he convinced the company to spend $700 million to fund EGR development.

On October 31, 2007, Navistar formally announced their intent to move forward with EGR as the company's strategy. The company statement included Ustian mentioning "I have publicly been an advocate of customer friendly emissions control solutions which do not add additional costs to our truck and bus customers. While SCR is a means to achieve the NOx reduction requirement for 2010, it comes with a steep cost to our customers. Our ability to achieve our goals without adding customer cost and inconvenience is a competitive advantage for International."

On November 24, 2008, Navistar revealed it would use EPA Credits in order to comply with the 2010 legislation.

In February 2009, Ustian touted the benefits of EGR technology as a key differentiator for the company's engines. However, by now, the rest of the industry had chosen to use compliant SCR technology. Ustian disagreed with SCR, saying "the other thing that EGR avoids is the risks of an SCR strategy. Read the label on this and it will show you that there are challenges with keeping control of using this technology: 'Store between 23 degrees and 68 degrees.' So essentially it says you can't throw it outside. You can't operate it in conditions above 85 [degrees] or below 12 [degrees]. You can, but, it will put the burden onto the customers."

Non-conformance penalties

The EPA recognized Navistar's imminent non-compliance and created a system of Non-Conformance Penalties (NCPs) that included a $1,919 fine for every non-compliant engine that Navistar sold. To bridge the gap, Navistar began using EPA credits it had previously earned for being compliant in lieu of paying fines. In August 2012, Navistar stated they would run out of EPA credits soon. Only days earlier the EPA announced increased new penalties of $3,744 per engine.

In March 2009, Navistar sued the EPA, claiming that the agency's guidance documents for SCR implementation were invalid because they were adopted without a public process and with input only from the SCR engine makers. Navistar and the EPA settled the lawsuit a year later.

Further masking the EGR problem were high military sales. In the company's 2010 10K report, Navistar cited orders for MRAPs as offsetting flat commercial sales due to the recession.

In January 2012, the EPA adopted an interim final rule that allowed Navistar to continue selling the engines subject to NCPs. Several Navistar competitors sued, and in June 2012 the same appeals court ruled that EPA's interim rule was invalid because it did not give the public notice and an opportunity for comment.

In the meantime, Navistar's EGR decision had led to significant reliability issues and quality problems (which were ultimately traceable to the fundamental physical reality that recirculation of exhaust gas introduces intrinsically abrasive soot and inherently corrosive acid gases back into the engine). Truck drivers began losing trust and confidence as Navistar vehicles were breaking down frequently. Consequently, they abandoned Navistar trucks in favor of competitors' trucks.

Legal issues (MaxxForce engines)

In December 2014, the United States Judicial Panel on Multidistrict Litigation ordered that 13 of 14 civil lawsuits brought against Navistar for MaxxForce engines would be consolidated into one case. The consolidated lawsuits say Navistar's use of Advanced Exhaust Gas Recirculation emission control system, or EGR, was defective and resulted in repeated engine failures and frequent repairs and downtime.

On December 16, 2014, Navistar reported a larger than expected fourth quarter net loss of $72 million. While sales rose 9 percent to $3 billion, the company cited restructuring and warranty costs as the main reasons for the loss. A day earlier, the company announced it would be closing its engine foundry in Indianapolis, resulting in the loss of 100 jobs and costing $11 million. The company estimated annual savings of $13 million in operating costs.

In March 2015, Navistar reported a first-quarter 2015 net loss of $42 million, or $0.52 per diluted share, compared to a first-quarter 2014 net loss of $248 million, or $3.05 per diluted share. Revenues in the quarter were $2.4 billion, up to $213 million or 10 percent, versus the first quarter of 2014. The higher revenues in the quarter were driven by a 17 percent year-over-year increase in charge outs for Class 6-8 trucks and buses in the United States and Canada. This included a 42 percent increase in school buses; a 25 percent increase in Class 6/7 medium trucks; a 7 percent increase in Class 8 heavy trucks; and a 5 percent increase in Class 8 severe service trucks. Higher sales in the company's export truck operations also contributed to the increase, partially offset by a decrease in used truck sales. The company finished the first quarter with a 27 percent year-over-year increase in order backlog for Class 6-8 trucks.

On June 4, 2015, Navistar reported a second-quarter net loss of $64 million, or 78 cents a share, compared with a year-earlier loss of $297 million, or $3.65 a share. Revenue fell to $2.69 billion from $2.75 billion. Analysts had expected a loss of 18 cents a share and revenue of $2.82 billion.

On June 9, 2015, Navistar named Jeff Sass as the new Senior VP of North American Truck Sales. Sass previously worked 20 years for rival Paccar.

On June 12, 2015, Mark Rachesky's MHR Fund Management LLC disclosed a 6% increased stake in Navistar, up to 15,446,562 shares. The firm now owns 18.9% of Navistar.

In July 2015, the EPA filed a civil lawsuit against Navistar seeking $300 million in fines over its use of non-compliant engines in its 2010-model trucks – engines that did not meet the agency's exhaust emission standards. "Because (Navistar) completed manufacturing and assembling processes for the subject engines in 2010 … each and every engine was 'produced' in 2010 and is therefore not a model 2009 engine," the complaint said. Navistar classified the engines as 2009 model year engines because it began assembling them in 2009. Navistar has stated they dispute the allegations and would "aggressively defend" their position.

On July 20, 2015, Navistar announced that it was refinancing the $697.5 million senior secured term loan facility of Navistar, Inc., which matures in August 2017, with a new $1.040 billion senior secured term loan, which will mature in August 2020. The refinancing will extend the maturity of the term loan facility and provide additional liquidity and financial flexibility for the company.

In March 2016, the Securities and Exchange Commission charged Navistar with misleading investors about its development of the advanced technology truck engine.

In August 2017, a Tennessee jury found that Navistar committed fraud and violated the Tennessee Consumer Practice Act in connection with the sale of 243 Navistar International ProStars with MaxxForce engines to Milan Supply Chain Solutions. It awarded $10.8 million in actual damages and $20 million in punitive damages. The trial included testimony from Jim Hebe, who previously was the senior vice president, North America Sales Operations. Hebe retired in October 2012. Hebe's testimony about the engine program mentioned that the company "did not test s**t". In a statement, Navistar said it is disappointed in the jury's verdict and is evaluating its options to challenge it, noting it has successfully defended similar claims in several jurisdictions, including dismissal of claims of fraud in courts in Texas, Wisconsin, Michigan, Indiana, Alabama, and Illinois.